1. Technical Field
The present invention relates generally to an improved data processing system, and in particular to a method, system, and product for indicating power status for field replaceable units (FRUs) where hierarchically encoded service indicators are used to indicate when service is needed.
2. Description of Related Art
Service indicators, such as LEDs, are typically used to help service technicians locate the correct component to be repaired on a computer system. On many small and mid-range computers, each field replaceable unit (FRU) has an unlabeled LED which represents the FRU that needs to be repaired. The LED is physically mounted on the FRU itself or the second level package that includes the FRU. Therefore, the LED does not need to be labeled since it is physically located on the FRU, or the FRU's outer package, that needs service. In these systems, there is a one-to-one correspondence between each FRU and the indicator that represents the FRU. Thus, in these systems, each FRU is associated with and represented by its own LED.
On high end systems, because of the density of the package and number of FRUs involved, a light strip is sometimes used to mount the LEDs in a visible location. Thus, instead of being mounted directly on the FRU or the second level package that includes the FRU, each LED is mounted on the light strip. The light strip includes an LED for each FRU in the system. In this example, there remains a one-to-one correspondence between FRUs and LEDs. Each individual FRU is associated with and represented by its own LED.
In some high end systems, all of these LEDs could total in the hundreds. This creates many problems. The light strip must be very large and located somewhere close to the central processing complex that includes the processing nodes, but not in the way of service technicians or airflow for cooling. There may be problems with lighting this large number of LEDs in standby mode of operation. And, it may be hard for the service technician to distinguish which LED is associated with which FRU because of the large number of LEDs. This then defeats the purpose of having LEDs.
In addition to the LED that indicates whether a particular FRU needs service, other indicators may be used to indicate whether a particular FRU is currently receiving power. Thus, each individual FRU will have one or more indicators that represent its status. When the power status of an FRU is to be indicated, the FRU will have two indicators associated with it, one to indicate service and one to indicate power status.
Some FRUs support concurrent replacement. Concurrent replacement means that an FRU may be replaced while the system is running. It is imperative that a service technician know the status of the power on the FRU before attempting to replace it. If the power is not in the correct state and the service technician attempts to replace the FRU, it could cause the system to checkstop and crash for what would otherwise have been a concurrent repair.
Therefore, a need exists for a method, system, and product indicating power status for field replaceable units (FRUs) where hierarchically encoded service indicators are used to indicate when service is needed.